Roll back dependency mikey179/vfsstream to 1.6.12

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

composer.json

@@ -38,7 +38,7 @@
         "laminas/laminas-coding-standard": "^3.0.1",
         "laminas/laminas-mvc": "^3.8.0",
         "laminas/laminas-servicemanager": "^3.23.0",
-        "mikey179/vfsstream": "2.0.x-dev",
+        "mikey179/vfsstream": "1.6.12",
         "phpunit/phpunit": "^10.5.38",
         "psalm/plugin-phpunit": "^0.19.0",
         "vimeo/psalm": "^5.26.1"